Could someone please tell me what this tree is?

It could be a laurel

Hello its a Laurel, and if you want to hard prune it then it responds very well, if you so wish you could come right down on it and take the overhang back too.

Thank You very much for your replies. I will take your advice Julien and prune it back.

There may be birds nest in it? There was one in mine when I pruned it right back.

Thanks for the advise, I will watch out for bird nest.

Cherry Laurel, though, not a Bay Laurel.

Yep, Cherry laurel, or more specifically, Prunus laurocerasus.